1. Field of the Invention
The present invention relates to a vehicle system, and particularly relates to eliminating the need for blocking at a merging section.
2. Description of the Related Art
Vehicles such as overhead travelling vehicles and auto-guided vehicles monitor vehicles in front thereof using a forward-looking sensor. However, at a merging section, it is difficult to simultaneously monitor other vehicles that enter the merging section, and, thus, a ground-side controller performs exclusive control such that the number of vehicles that are simultaneously present in the merging section is restricted to one or zero. See, for example, Japanese Patent No. 4835937. This control, which is referred to as blocking, increases the amount of processing performed by the ground-side controller, and restricts the number of vehicles that are allowed to pass through the merging section. Thus, it is preferable not to use blocking in the control at the merging section.
Hereinafter, an example that does not use blocking will be described. Japanese Patent No. 4798554 has proposed a system for controlling the positions of vehicles using a ground-side controller. In this system, each vehicle reports its current position and the like in each control cycle, the ground-side controller gives an instruction about a target position, and the vehicle controls its velocity so as to reach the given target position. In this system, blocking is replaced with instructions about target positions. However, Japanese Patent No. 4798554 has not conducted any particular research on control of the order for passing through the merging section and the like. Alternatively, for the purpose of eliminating the need for blocking, for example, RFID is conceivable in which a flag indicating that a vehicle is travelling is set when the vehicle enters the merging section, and is cancelled when the vehicle has passed through the merging section. Communication between vehicles using RFID eliminates the need for blocking. However, according to this configuration, a flag has to be reliably set and cancelled in the RFID system.